Yesterday I went to purchase some vermiculite for incubators. Normally cheap and easily available, I found it only on the fourth attempt. The nurseryman said that there's concern about the potential for respiratory problems similar to those noted in connection with asbestos. WalMart, Lowe's, K-Mart and Home Depot have discontinued the stuff in what may become an industry-wide trend. The nursery had only four small bags. So if you use the stuff you may want to stock up if you can find some.